Double-acting, casing frame hydraulic press

ABSTRACT

The subject of the present invention is a double-acting hydraulic press built with a monolithic frame of a casing type. Fixed slidably within the frame are four columns on which the press platen is rigidly mounted. In this manner there are obtained two working zones of the press: a top and bottom zone, thus eliminating the idle stroke of the press. Both ends of the columns outside of the frame of a casing type are linked together with two plates which are operating jointly with power plungers. The power plungers are working inside the cylinders mounted on the bottom and the top plate of the frame. Such a design ensures a reciprocal reduction of reactions from the cylinder and from the tool, these reactions affecting the frame which in this instance does not show any practical deformation.

[4 June 25, 1974 DOUBLE-ACTING, CASING FRAME HYDRAULIC PRESS Edmund Nowak, Warszawa, Poland Przedsiebiorstwo Doswiadczalne Pras Automatycznych' Aug. 15, 1972 Inventor:

Assignee:

Filed:

Appl. No.:

Foreign Application Priority Data Aug. 16, 1971 Poland 150044 US. Cl. 100/209, 100/269 R Int. Cl B30b l/34, B30b 15/06 Field of Search 100/209, 214,269 R;

425/450 R, DIG. 205

References Cited UNITED STATES PATENTS FOREIGN PATENTS OR APPLICATIONS 411,413 6/1934 Great Britain 100/209 Primary Examiner-Harvey C. Hornsby Assistant ExaminerPhilip R. Coe Attorney, Agent, or Firm-Edwin Greigg 5 7] ABSTRACT The subject of the present invention is a double-acting hydraulic press built with a monolithic frame of a casing type. Fixed slidably within the frame are four columns on which the press platen is rigidly mounted. In

this manner there are obtained two working zones of the pressza top and bottom zone, thus eliminating the idle stroke of the press. Both ends of the columns outsideof the frame of a casing type are linked together with two plates which are operating jointly with power plungers. The power plungers are working inside the cylinders mounted on the bottom and the top plate of the frame. Such a design ensures a reciprocal reduction of reactions from the cylinder and from the tool, these reactions affecting the frame which in this instance does not show any practical deformation.

6 Claims, 1 Drawing lFigure DOUBLE-ACTING, CASING FRAME HYDRAULIC PRESS i The subject of the present invention is a doubleacting, casing frame hydraulic press equipped with a system of plungers located in the bottom and top part of the frame, and with a movable platen fixed on sliding columns. I

The known double-acting hydraulic presses can be classified, according to their construction, as the presses of a column-type carrying unit. A system of several columns, consisting, for instance, of four or of eight columns, comprehends two plates, top and bottom plate, with a platen fixed in between these two plates on sliding columns.

The hydraulic presses of this type are equipped with a single-acting power transmission system, usually with a bottom system. Also known are the constructions of double-acting hydraulic presses with a top and a bottom power transmission system, the strokes in such case of a top and a bottom platen following, during the operation cycle, one after the other, thus reducing the frequency of press operation.

An extremely important problem with double-acting hydraulic presses is a suitably high rigidity of the system transmitting the power from the power cylinders and pistons to the platen, and therefore of a suitably high rigidity of the whole press structure.

Used, until recently, as coupling elements between a power piston and a platen, or platens, were the columnsleeve type systems which did not provide for the required rigidity of the press. For this-reason the constructions of double-acting presses were provided with a very rigid power transmission system in order to compensate for a lower rigidity of a column-sleeve type system, with the platen mounted on this system.

A substantial drawback of column-sleeve type systems of double acting presses is a comparatively low rigidity of these systems. Although the application of column-casing type frames considerably improves the rigidity of presses, but on the other hand the fact that the casing frame is braced with columns, induces a real limitation for the press rigidity.

Application of a rigid power transmission system brings about the necessity for an intricately developed system reflecting unfavorably on the weight of the press, while the application of rigid sleeve type systems, these systems coupling the platen with power transmission systems, entails that bending-torsion moments are transmitted from the working zone of the press to the power system, thus producing a slanting of the piston in relation to the cylinder, a slating that may result in seizure of the piston. This latter imperfection is common for the presses of column type, frame type, or column-casing type carrying systems in which the bending-torsion stresses, produced in the working zone of the press and acting on a platen moving along column-type or flat guides, are transmitted to pistons and power cylinders, thus causing a considerable strain 2 costly technology of machining, as well as not requiring a bilateral control of the platen stroke.

The assumed technical problems havebeen solved in such a manner, that the invented press includes a frame which forms a monolithic casing structure with power cylinders, top and bottom power cylinders together with plungers, mounted on the frame, said plungers operating jointly with top and bottom plates fixed on elastic bars screwed into the columns. Bolted to the power cylinders are the top and bottom ring gears, these ring gears operating jointly with the said top and bottom plates and being coupled with worm screws, while between the bottoms of cylinders and plungers the springs are provided. The platen in the invented press is rigidly fixed on the column.

The basic noteworthy feature of a monolithic casing frame is its exceptionally high structural strength allowing to cope with high bending-torsion stresses. The fact that the columns are coupled, through the elastic bars, with the top and bottom plates and with the top and bottom power plungers, considerably simplifies the power system, the elastic bars being at the same time. the elements which compensate the harmful effects of bending-torsion stresses which generate in the working zones of the press and act upon the plungers and cylinders, said plungers and cylinders being, in fact, not exposed in the invented system to any transverse stresses.

Consequently, the platen rigidly fixed on columns does not transmit to the cylinders and plungers any torsional stresses which become now closed in the frame.

The fact that the press cylinders are mounted on the top and bottom plates. of the casing frame eliminates deformation of these plates, since the tools regulation stresses acting upon these plates and the stresses caused by the cylinder pressure are reducing each other.

The ring gears bolted to thecylinders, these ring gears operating jointly with the top and bottom plates, provide for the adjustment, by turning of the worm screws, of the stroke of the platen movable in both directions, as well as allow, in case of tool failure, to charge the platen position and to increase the tool clearance in the top or bottom working zone of the press and to rectify thedefect without the necessity of dismantling the tool from the press.

The springs located between the cylinder bottom and theplunger prevent dropping of the press at idle periods, keeping it in a middle position.

An embodiment of the invented press will now be described by way of example with reference to the drawing in which the press is illustrated axially in half section.

As is seen in the FIGURE, a press frame 1 forms a monolithic structure of a casing type. Mounted slidably in the frame, in slide or ball guides, are columns 2 with i a platen 3 mounted on these columns. The platen is rig in these elements and their displacement resulting in a premature wear of the whole press.

The purpose of the present invention is to obviate the above-mentioned shortcoming and imperfections by developing a double-acting hydraulic press characterized by the highest possible rigidity of the press frame, this press being equipped with a combined top and bottom power system, and not requiring a complex and top cylinder plunger 9, said plungers operating jointly with a bottom plate 11 and a top plate 17.

Plates 11 and 17 are mounted, by means of nuts 12, on elastic bars 14 and 16, said bars being screwed into columns 2. Bolted to the cylinders 5 and 8 are ring gears: a bottom ring gear 7 and a top ring gear 10, these rings meshing with worm screws 13 operate jointly with plates 11 and 17.

Provided between the cylinder bottoms and the plungers are springs 15.

The base of the press is indicated by broken lines.

The invented press operates as follows:

A hydraulic distributor (not shown in the drawing) directs the oil first to the bottom cylinder 5 and beneath the working face of the plunger, thus causing the plunger 6 of bottom cylinder to move downwardly, and a bottom spring 15 to expand. ln consequence of this movement the system consisting of bottom plate 11, elastic bars 14 and 16, columns 2, and platen 3 moves also downwardly until the forming operation takes place in the press bottom working zone. At the same time the top plate 17 presses against the top plunger 9 thus causing a downward motion of this plunger and a discharge of oil from the top cylinder 8, while the top a spring 15 becomes compressed. Following this, the distributor begins to direct the oil to the top cylinder and beneath the working face of the top cylinder plunger, this plunger beginning thus its upward motion. In consequence of this motion the system consisting of top plate 17, elastic bars 16, columns 2, and platen 3 begins to move upward until the forming operation takes place in the press top working zone.

At the same time the oil is pressed out from beneath the bottom plunger, and the stroke is limited by the extent to which the ring gear 7 or 10 advances. During their compression the springs 15 are cushioning the impact of the press against the ring 7 or 10.

That which is claimed is:

l. A double-acting hydraulic press comprising, in combination:

a. a monolithic frame having two spaced-apart rigid structural members, each of said members having an inwardly facing surface and an outwardly facing surface, each of said inwardly facing surfaces constituting respective working surfaces of the press;

b. a platen positioned between said structural members; said platen having respective working surfaces facing toward said inwardly facing surfaces;

c. a first power system positioned on a first one of said members on its said outwardly facing surface;

d. a second power system positioned on a second one of said members on its said outwardly facing surface;

e. respective means coupling said platen to each of said power systems; and

f. means for allowing hydraulic fluid to be selectively applied to said first and said second power systems;

whereby said platen may be moved alternatingly toward respective ones of said inwardly facing surfaces of said structural members which, with said working surfaces of said platen, define first and second working stations of the press.

2. A double-acting hydraulic press as claimed in claim I, wherein said first power system includes a bottom cylinder and a bottom plunger and said second power system includes a top cylinder and a top plunger; and further comprising a bottom plate and a top plate, these plates being positioned outside of said frame and being mounted on respective elastic bars; and wherein said means coupling said platen to each of said power systems include respective columns connected between said platen and said elastic bars.

3. A double-acting hydraulic press as claimed in claim 2, further including a bottom ring gear bolted to said bottom cylinder and a top ring gear bolted to said top cylinder and respective drive means meshed with said ring gears.

4. A double-acting hydraulic press as claimed in claim 3, further including a first spring means positioned between said bottom plunger and the bottom of said bottom cylinder, and a second spring means positioned between said top plunger and the bottom of said top cylinder.

5. A double-acting hydraulic press as claimed in claim 2, further including a first spring means positioned between said bottom plunger and the bottom of said bottom cylinder, and a second spring means positioned between said top plunger and the bottom of said top cylinder.

6. A double-acting hydraulic press as claimed in claim 2, wherein said platen is rigidly fixed on said col- 

1. A double-acting hydraulic press comprising, in combination: a. a monolithic frame having two spaced-apart rigid structural members, each of said members having an inwardly facing surface and an outwardly facing surface, each of said inwardly facing surfaces constituting respective working surfaces of the press; b. a platen positioned between said structural members; said platen having respective working surfaces facing toward said inwardly facing surfaces; c. a first power system positioned on a first one of said members on its said outwardly facing surface; d. a second power system positioned on a second one of said members on its said outwardly facing surface; e. respective means coupling said platen to each of said power systems; and f. means for allowing hydraulic fluid to be selectively applied to said first and said second power systems; whereby said platen may be moved alternatingly toward respective ones of said inwardly facing surfaces of said structural members which, with said working surfaces of said platen, define first and second working stations of the press.
 2. A double-acting hydraulic press as claimed in claim 1, wherein said first power system includes a bottom cylinder and a bottom plunger and said second power system includes a top cylinder and a top plunger; and further comprising a bottom plate and a top plate, these plates being positioned outside of said frame and being mounted on respective elastic bars; and wherein said means coupling said platen to each of said power systems include respective columns connected between said platen and said elastic bars.
 3. A double-acting hydraulic press as claimed in claim 2, further including a bottom ring gear bolted to said bottom cylinder and a top ring gear bolted to said top cylinder and respective drive means meshed with said ring gears.
 4. A double-acting hydraulic press as claimed in claim 3, further including a first spring means positioned between said bottom plunger and the bottom of said boTtom cylinder, and a second spring means positioned between said top plunger and the bottom of said top cylinder.
 5. A double-acting hydraulic press as claimed in claim 2, further including a first spring means positioned between said bottom plunger and the bottom of said bottom cylinder, and a second spring means positioned between said top plunger and the bottom of said top cylinder.
 6. A double-acting hydraulic press as claimed in claim 2, wherein said platen is rigidly fixed on said columns. 